Arcane items of medical obscurity are the neurologist's lifeblood. We can figure stuff out. This blogger is interested in diseases that affect people-- go somewhere else for results of rat research. Information is meant to be advanced but clinically relevant esoterica.

Sunday, March 15, 2009

Pearls on antibody testing in MG

1. AchR antibody is positive in 80-85 % of patients with MG, but only 55 % of pure ocular disease2. Less than one percent of patients have pure blocking antibodies (others may have associated with binding antibodies) and so blocking antibodies are of little clinical use.3. Modulating antibodies cross link the receptor and modulate their rate of degradation. It is most helpful as a test when the level of binding antibody is negative which is 3-4 %.4. High levels of modulating antibodies, like anti striated muscle antibodies, occur in association with lymphoma, although can occur sporadically too especially in old.5. MuSK antibody, important in clustering of receptors in NMJ, are positive in 40 % of AchR negative patients, only occassionally in those with pure ocular disease.